TWI247339B - Lithographic printing with polarized light - Google Patents

Abstract

The present invention provides systems and methods for improved lithographic printing with polarized light. In embodiments of the present invention, polarized light (radially or tangentially polarized) is used to illuminate a phase-shift mask (PSM) and produce an exposure beam. A negative photoresist layer is then exposed by light in the exposure beam. A chromeless PSM can be used. In further embodiments of the present invention, radially polarized light is used to illuminate a mask and produce an exposure beam. A positive photoresist layer is then exposed by light in the exposure beam. The mask can be an attenuating PSM or binary mask. A very high image quality is obtained even when printing contact holes at various pitches in low k applications.

Description

1247339 (1) Description of the Invention [Technical Field] The present invention relates to a high number of apertures and immersion lithography. [Prior Art] The requirements for lithography tools and techniques are increasing with high resolution printing patterns. For example, in the fabrication of semiconductor dies or wafers, patterns of circuit characteristics such as lines, contact holes or other components are often required to be printed at high resolution to improve the packing density of the circuit components and to reduce the dot pitch of the pattern. Certain circuit characteristics, such as contact holes or through holes, are particularly difficult to manufacture. A well-known parameter related to lithography resolution is the critical dimension (CD) ° CD is the minimum geometric size, which can be formed using semiconductor technology and circuit fabrication. The critical dimensions can be illustrated by the following function: CD = k (λ/ΝΑ) where λ is the wavelength used for the lithography, ΝΑ is the number 値 aperture, and k is the dielectric constant. In the trend of lithography, CD is reduced by increasing the number of apertures by decreasing the wavelength used. Printing in low-k applications is difficult. For example, when k 値 is less than 0·5, the contact hole is difficult to print. High quality contrast images of sufficient quality, including clustered contact holes, such as contact arrays, are particularly difficult to print. Techniques that use very high NA and off-axis illumination to enhance contrast have been used' but their techniques cannot be used for small dot pitches. For example, at a wavelength of 157 nm and 0.9 3 N A, the finite dot pitch (mainly by resolution) is about 1 35 nm (k = 0.4) - this is too high for some applications. At the same time, the dot pitch of -5- (2) 1247339 may be prohibited. This means that if the illumination is optimal for a particular dot pitch, then other dot pitches may not be printed at the same time. The forbidden dot pitch can be displayed at a low normalized image registration slope (NILS) or poor CD control of the forbidden dot pitch. SUMMARY OF THE INVENTION The present invention provides a system and method for improving lithography printing using polarized light. In an embodiment of the invention, polarized light (e.g., radiated, tangential, or custom polarized) is used to illuminate a phase shift mask (PSM) and produce an exposure beam. The negative photoresist layer is then exposed via the light of the exposure beam. A chrome free PSM can be used. In one embodiment, the radio-polarized light system is used to combine chrome-free PSM, Cartesian quadrupole (C-quad) illumination, and negative photoresist. Even when used in low-k applications, it is possible to obtain extremely high image quality by printing contact holes of different dot pitches. Avoiding the prohibition of the dot pitch. In a further embodiment of the invention, the radially polarized light is used to illuminate the mask and produce an exposure beam. The positive photoresist layer is then exposed via the light of the exposure beam. The mask can be an attenuated PS Μ or a binary mask. In one embodiment, the radially polarized light is used in conjunction with an attenuated phase shift mask or binary mask, a standard diagonal four pole illumination, and a positive photoresist. Even when applied in low-k applications, the contact holes of different dot pitches can be printed to achieve extremely high image quality. Custom polarization can be used to further improve printing. The custom polarization may be, for example, combined with radiation and tangential polarization. In addition, alternating PSM can also be used to improve print quality. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention, characteristics -6-(3) 1247339 and advantages, and structures and operations of different embodiments of the present invention will be described in detail with reference to the accompanying drawings. Components The present invention will be described with reference to the accompanying drawings. The first ij in the figure is typically indicated by the leftmost digit of the relevant number. [Embodiment] Table of Contents 1. System Overview 2. Discussion and Simulation Results A. Introduction B. Resolution B1. Theoretical resolution limit. B2. Resolution of optical off-axis illumination lithography C. Polarization C1. Simulation Experiment C2. Polarization effect mask for image quality, and C3. Polarized light, chrome-free PSM, negative photoresist C4. Radiated polarized light, attenuated phase shift mask or binary masking photoresist D. Chromium-free alternating PSM Polarization D1. Chromium-free alternating PSM combined with radioactive polarization, nm point from nest contact D 2. Chromium-free contact with radioactive polarization. D3. Custom polarization E. Soaking micro Shadow 100- 1247339 (4) F. Although it is easy to discuss. People who are familiar with the spirit and scope of the craft. The present invention 1. System Overview FIG. 1 is a perspective view of a laser of an illumination source 102 as understood by the present invention. The pre-existing 'pattern' in the emitter generator is not limited to the illumination source 102, such as a 102-issued waveplate. Pattern Ultraviolet Radiation (EUV) is a specific specification and design, but it should be understood that it is understood by those skilled in the art that other specifications and designs may be used without departing from the invention. It will be apparent to those skilled in the art that the present invention is also applicable to a number of systems and methods for improving lithographic printing with polarized light. A lithography system 100 in accordance with an embodiment of the present invention. Pre-polarized illumination is emitted along an optical path at an actual source 102. Although pre-polarized illumination is mentioned herein, those skilled in the art will also be able to use unpolarized illumination. An example of pre-polarized light may be to emit a laser beam having a tendency to be approximately linearly polarized, and the polarizer may be attached to the polarized illumination source 102 and then pass through the pattern polarization device 1 0 4 . As described herein, the polarization device 104 is defined to surround the polarization device, including conventional and I-polarization and wave plates. If the pre-polarized light system is emitted, the pattern polarization device 104 can be a polarized device or a plurality of polarizers or wave plates. If the unpolarized light system is illuminated by an illumination source, then the pattern polarization device 104 shapes the pre-polarized illumination light for the polarization polarizer instead of the chemical device 104.

-8- (5) Design of 1247339, such as polarization pattern and intensity pattern. For example, pattern polarization device 104 can shape pre-polarized illumination light into radio-polarized light, tangentially polarized light, or light having a custom polarization. In one embodiment, the illumination light is a quadrupole illumination, such as a Cartesian quadrupole (C-quad) illumination. Although quadrupole illumination is used herein as an example, those skilled in the art will appreciate that any source illumination can be used. Illumination illuminates the mask 106. The mask 106 produces a pattern in the illumination light. It will be understood by those skilled in the art that the mask 106 can be any type of mask or line. In an embodiment of the invention, the mask 106 is a binary mask. In other embodiments, the mask 106 is a phase shifting mask (PSM), such as a chromium-free PSM, an alternating PSM, or an attenuated PSM. The light comprising the mask pattern then passes through projection optics 108, which further adapts and processes the light. Projection optics 108 can include one element or a plurality of optical elements. Projection optics 108 produces an exposure beam that continues along the optical path. Finally, the exposure beam is exposed to the wafer 1 1 依据 according to the pattern it contains. In an embodiment of the invention, the wafer 110 is covered by a negative photoresist layer. In one embodiment, the radio-polarized light system is used to combine chrome-free PSM, Cartesian quadrupole (C-quad) illumination, and negative photoresist. Even when used in low-k applications, printing contact holes of different dot pitches can achieve extremely high image quality. Avoid prohibiting the dot pitch. In other embodiments of the invention, the wafer 1 1 is covered by a positive photoresist layer. For example, the radially polarized light is used in one embodiment to mask 106 and produce an exposure beam. A positive photoresist layer is then exposed to light in the exposure beam by -9 - 1247339 (6) light. In other embodiments, the radioactively polarized light is used in conjunction with an attenuated phase shift mask or binary mask, standard diagonal quadrupole illumination, and a positive photoresist. Even when used in low-k applications, it is possible to obtain extremely high image quality by printing contact holes of different dot pitches. Figure 2 is an example of another lithography system 2000 in which the present invention can be accomplished. Polarized illumination source 02 and mask 1 〇6 perform the same function as described in System 1 。. However, in system 200, pattern polarization device 202 is included in a projection optical instrument. Like the pattern polarization device 104, the pattern polarization device 02 shapes the pre-polarized illumination light into various preset designs, such as a radio polarization design, a tangential polarization design, or a custom polarization design. Optical elements that are further shaped and adapted to illuminate light can be placed in front of or behind the pattern polarizing device 202. Optical elements such as channels are shown as projection optics 204 A and 204 B and an exposure beam that continues along the optical path is fabricated. After shaping through the patterning polarization device 202 and the projection optics 204A and 024B, the polarized light is exposed to the wafer 1 10 in accordance with the pattern of the mask 106. Wafer 110 may be covered by a positive or negative photoresist layer. 2. DISCUSSION AND SIMULATION RESULTS The following discussion and simulation results are provided to further illustrate the aspects and features of the embodiments of the present invention and are not intended to limit the invention. The inventors used KLA-Tencor's Prolith*TM 7.1 lithography simulation system to compare many methods for printing 5 0/5 0-nm nest contact holes. Methods used in canals, etc. include: off-axis four-pole illumination, and phase shift masks with optimal illumination polarization; chrome-free alternating phase shift masks combined with specific polarization modes (CAPS Μ 1247339 (7) ): immersion lithography with a very high number of apertures (ΝΑ), wavelength 157-nm; and far ultraviolet radiation (EUV) lithography. The inventors have discovered that the limitations of optical off-axis illumination techniques can be promoted by the use of radio-polarization and how the mask distortion (background transmission) is used to optimize the image. The resolution limit can be further advanced by two-dimensional chromium-free alternating PSM in combination with radio-polarization. With the polarization enhancement according to the embodiment of the present invention, a high contrast image can be obtained, and a negative photoresist can be used to print a high quality contact hole of a l〇〇-nm dot pitch. In an exemplary application including immersion, radio-polarization in accordance with embodiments of the present invention can further enhance image quality. The inventors further studied the results obtained by far-reaching ultraviolet radiation (EUV) wavelengths, and found that it is possible to provide a superior position for printing a contact hole of a 100-nm dot pitch at an EUV wavelength and a low NA. A. Introduction At present, for optical lithography, generating a 50-nm contact with a 10 Ο-nm dot pitch is a challenge. The industry guidelines for semiconductor devices require a 50-nm junction by 2008. To achieve this capability, current optical lithography requires significant expansion before EUV is widely used. Even with high-NA optical instruments using 157-nm wavelengths, conventional contrast enhancement techniques such as optical off-axis illumination and attenuation P S 均 are insufficient to print a sufficiently high quality contact hole of 1 0 0 · n m pitch. In addition to quadrupole illumination with attenuated PSM, resolution enhancement techniques are needed to print contacts at l〇〇-nm pitch. Referring to FIG. 3A, an enlarged view of a wafer having a contact hole. A resist layer 322 is attached to the wafer surface 304. A lithography system (not shown) exposes the resist layer 310, -11 - (8) 1247339 to create contact holes 306. Fig. 3B is an image of the contact hole pattern when viewed from the above. The simulation is used to view the optimal printing technique for clustered contacts in accordance with embodiments of the present invention. The inventors used Pro lithTM 7.1 to explore techniques for improving the printing capabilities of contact windows. First, the inventors simulated the traditional lithography of a high-number 値 aperture 157-nm system and set the minimum dot pitch for printing with appropriate image contrast. Second, the inventors are increasingly modifying the technology to improve the resolution capabilities. In this way, the present invention explores the chrome-free phase shift mask by first optimizing the polarization of the illumination, and then uses wavelength shortening methods such as immersion lithography and EUV lithography to display and out-of-light illumination and 6 Improvement results for the initial state of the % attenuated phase shift mask (PSM). B. Resolution First, the theory of the resolution of the portion of the contact is printed in the text. This theory helps explain how we enhance the system resolution of the contact array. B1·Theoretical resolution limit For the two-dimensional periodic pattern of the X-direction point distance Ρχ and the y-direction point distance Py, the mask spectrum is a non-zero discrete spatial frequency, and the χ and y parts are inversely proportional to the point distance: (Equation) where η and m are integers (〇, +/-1, +/_2, +/-3, etc.) In general, it is convenient to handle normalized spatial frequencies. That is: -12- (9) 1247339 (equation) In addition to the zero point, at least the first three diffraction points must be extracted by the lens to obtain sufficient resolution, namely (0,0), (〇,1), (1,〇), and (1,1) points. For illumination on the optical axis, this requirement is expressed as follows: (Equation) Place a square within a quarter circle of the unit radius (refer to the diffraction pattern in Figure 4A), ie if Px = py = P, Bay IJ (Equation) and has diagonal off-axis illumination: (Equation) Place a square within the entire unit radius circle (refer to the diffraction pattern in Figure 4B), ie if PX = P y = P, Bay 1J (Equation) By using this theory, we can form group contact holes at 157-nm and 0.93 NA, where the theoretical imageable minimum dot pitch (X and y directions) is 240 nm on the optical axis, outside the optical axis. The illumination is 120 nm. The inventors can simulate to further explore the conditions outside the optical axis. B 2. Resolution ability of the optical axis external illumination lithography The conventional optical axis illumination advances to the optical axis external illumination to improve the resolution -13 - 1247339 (10) degrees. The self-generated image is not sufficient to meet certain quality standards that ensure sufficient processing of the resist space. To print nested contact holes, the assumed contrast and normalized image registration slope (NILS) must be greater than 0.5 and 1.5, respectively. Please refer to SPIE 4691:503 (2 0 0 2 ), Graeupner, P, et al., "The resolution of contacts below 100 nm with argon fluoride (ArF)." In response to these needs, the inventors judged the minimum dot pitch at which the nest contact holes can be printed. First, consider the high quality of printed cluster holes with low k. These conditions include: 0.9/0.1 quadrupole illumination of a diagonal pole (where 〇.9 is the center-to-pole distance, 〇·1 is the pole radius)

— 0.93 NA 6% 1:1 attenuation PS 非 The non-polarized light incident on a reticle is gradually reduced by the dot pitch, as long as the pattern pitch is 1 3 4 nm (ie, 6 7 -nm junction and spacing), The image contrast in the air in the spot direction (C 0 ) can be kept above 〇·5. It has an NILS of ~〗·5. The final image is shown in Figure 5. By changing the illumination on the optical axis to off-axis illumination, the print resolution of the contacts can be improved from 240 nm to 134 nm. Obviously, when using slightly different N A or quadrupoles, the minimum resolvable dot pitch defined above will change. This definition cannot take into account the depth of focus (D 0 F ): therefore, it is expected that the minimum printable dot pitch should be large. This example is sufficient to show that a relatively unconventional device must be used to cause the resolution limit to drop to 1 〇〇_nm. _ 14_ 1247339 (11) C. Polarization Refer to the literature on "polarization pairing" in which the electric field vectors overlap, resulting in maximum interference and highest image quality. See SPIE 4346-.1 522 (2 00 1), Ma, Z et al., "Attenuation of phase-change mask image illumination consistency and polarization effects." Linearly polarized illumination has been used to improve the image quality of a properly oriented line, but no specific polarization system has been suggested for use in the contact holes of embodiments of the present invention. In the following discussion, the effect of using radiation and tangentially polarized light will be disclosed. These two types of polarization enhance the image quality of the contact holes. While radiation and tangential polarization are discussed herein, those skilled in the art will appreciate that other polarizations disclosed herein, including custom polarization, can also be used to enhance image quality. Unless otherwise stated, the conditions are as follows, NA is 0.93, illumination is 0.9 / 0.] Diagonal quadrupole with a wavelength of 157.6 nm. C1. Simulation Experiments This operation uses the ProlithTM 7.1 simulator to provide three polarization mode options called X-polarization, y-polarization, and non-polarization. Non-polarized mode shadows can be obtained by adding X-polarization and y-north mode airborne images. Protic TM 7.1 can be used to simulate tangential or radio-polarized light with simple manipulation of the mask orientation. An example of a one-way manipulation is depicted in FIG. Assuming the pole is small enough, the inventor first rotated the pattern by 45°. They then calculate the first image using X-direction dipole illumination with X or y polarized light (X polarization for radio illumination and y polarization for tangent illumination). The second image is then calculated using y-azimuth dipole illumination with -15-1247339 (12) x or y polarized light (y-polarization for tangential illumination and x-polarization for radiation illumination). Finally, add the two images to get the final image. C2. Polarization Effect of Image Quality Comparing Figures 7A and 7B, respectively, images using radiation-tangential polarization according to the present invention are shown. The difference between tangential polarization and radio polarization is depicted in Figures 10A and 10B. As shown in Figure 002, the direction of the polarization vector changes irregularly when the light is non-polarized. However, as shown in Fig. 106, once the non-polarized light passes through the tangential polarizer 1 004, the light becomes tangentially polarized. Once the light such as the channel becomes tangentially polarized, the polarization vector is uniformly circled at the center. The situation of radio polarization is slightly different. As shown in Fig. 10B, when the non-polarized light 1 0 02 passes through the radio-polarizer 1 00 8 , the light becomes radio-polarized light 1 0 1 0. Once the light such as the channel becomes radio-polarized, the polarization vector is uniformly radiated from the central position. The diagonal direction shows the diagonal lines in Figures 7 A and 7 B. The contrast of the direction of the polarization of the radiation is extremely high, that is, 0 · 8 8 , and the contrast of the tangential polarization is extremely low (〇 · I 9 ). At 45 degrees in the direction of the pitch, the contrast between the two types is high. For radiated polarized light, image matching can be optimized by changing the contact hole width (ie, mask deflection) until the contrast between the rectangle and the diagonal direction is the same (for tangential polarization, and No such improvements were found). In one embodiment, the contact hole width of 8 5 nm (ie, [8 _nm mask skew) -16- (13) 1247339 produces a uniform contrast of 134 nm pitch (approximately equal to rectangular and diagonal contrast) ° Alternatively, the background transmission of the mask can be modified to achieve the same effect. The inventors have found that the image quality produced by radioactively polarized light is superior to that produced by unpolarized light, even outside the focus. The improved resolution provided by the optimization of illumination polarization is examined. The minimum dot pitch can be reduced to 1.25 nm and the best contact hole width is found. For radio polarization, a sharp side lobe can be observed with a small contact hole width. The side lobes disappear as the contact hole width gradually increases from 50 nm to 75 nm. This is followed by a more consistent contact perimeter contrast distribution. This result shows that the radiated polarization provides an NILS improvement that exceeds 30% of unpolarized light. Figures 8A-8C depict a comparison of the three polarization states in accordance with the present invention. In each of the channels, etc., the direction of the dot pitch is shown. Figure 8A shows an airborne image using non-polarized quadrupole illumination at a 75 nm junction width. Figure 8B shows an airborne image illuminated with a tangentially polarized quadrupole at a junction width of 75 nm. Finally, Figure 8C shows an airborne image using a radio-polarized quadrupole illumination at a 75 nm junction width. Polarized illumination improves the resolution limit from 1 3 4 n m to 125 nm. Channels and other diagrams use radiated polarized light and the minimum contrast requirement of 〇·5 (1·5 NILS requirement). C3. Polarized Light, Chromium-Free PSM, Negative Light Resis In one embodiment of the invention, polarized light (radiation or tangential polarization) is used to illuminate the phase shift mask (PSM) and produce an exposure beam. A negative light • 17- (14) 1247339 The resist layer is then exposed by the light of the exposure beam. A chrome-free PSM can be used. In one embodiment, the radio-polarized light system is used to combine chrome-free PSM, Cartesian quadrupole (C-quad) illumination, and negative photoresist. Extremely high image quality is achieved even when printing clusters or nested contact holes in low-k applications. Avoiding the prohibition of the dot pitch. In one embodiment, the radio-polarized light system is used to combine chrome-free PSM, Cartesian quadrupole illumination, and negative photoresist to advance resolution to k = 0.29. The invention is not limited to Descartes quadrupole illumination. Further examples include, but are not limited to, quasar illumination, illumination with four fold symmetry, or any other illumination that is similar to quadrupole illumination. According to the simulations performed by the inventors on the PROLITHTM 7.1 system, near-perfect image contrast can be produced when using negative and radio-polarized illumination. , : Figures 9A - 9C show the polarization effect of the image quality in the simulation results obtained by the inventors. The results shown in Figures 9A-9C are simulated with a 1 〇〇 nm pitch, a chrome-free PSM contact hole with a wavelength of 157 nm, a 0.93 NA, and a resistivity of 1.78. Fig. 9A shows a poor contrast image of the obtained contact hole in the case of using non-polarized light and four-pole illumination. Figure 9 shows a poor contrast image of the contact holes obtained using tangentially polarized light and four-pole illumination. Fig. 9C shows a high contrast image of the contact hole obtained in the case of the radio-polarized light and the four-pole illumination according to an embodiment of the present invention. The minimum contrast of the three types of polarization in this example is as follows: -18- (15) 1247339 Polarization state minimum contrast non-polarization 0.67 Tangential polarization 0.44 Radiation polarization 1.0 In addition, this technique can be used even at low k factors. Use (for example, k equals 0.26 and the contrast is greater than 0.75). As shown in Figures 1 1 A and 1 1B, there is no prohibited dot pitch for this method. Figures 11A and 11B each depict CD (in nm) and NILS in the range of 100 to 900 nm dots in accordance with the present invention. Figures 11A and 11B show that under all simulated dot pitches (pitch range 100 to 900 nm, each pitch is 25 nm), NILS is not less than 2.9, indicating that all dot pitches can be printed simultaneously with a good space. . C4. Radiated Polarized Light, Attenuated Phase Shift Mask or Binary Mask, and Positive Light Resis In a further embodiment of the invention, the radioactively polarized light is used to illuminate a phase shift mask (PSM) and produce an exposure beam. A positive photoresist layer is then exposed by the light of the exposure beam. The mask can be an attenuated PSM or a binary mask. FIG. 12 shows an example of attenuating the phase shift mask 1 200. For ease of explanation, only the cell 1202 is described. The central portion 1204 of the grid 202 is a 100% transmitted area 'that means that all of the light of a certain phase passes through the area. For example, central portion 1 204 can transmit all phase turns. Light. The outer portion of the cell 12〇2 (16) 1247339 1 206 causes attenuation, in which a lower percentage of light of other phases is transmitted. For example, as shown in Fig. 12, the peripheral portion 1206 allows only 6% of the light of the phase 180° to pass. Alternatively, a binary PSM can be used in the present invention. Figure 13 depicts an example of a binary phase shift mask 1 3 。. For ease of illustration, only the lattice 1 3 02 of the binary migration mask 1 3 00 is described. Much like the central portion 1204 of the attenuated phase shift mask 1 200, the central portion 1304 of the binary phase shift mask 1300 allows 100% of the light to pass through. However, the peripheral portion 1 3 06 prevents all light from passing through, rather than allowing a reduced degree of light to pass through. In other words, the peripheral portion 1306 has a transfer rate of 0%. In one embodiment, the radially polarized light is used in conjunction with an attenuated phase shift mask or binary mask, a standard pair of angle quadrupole illumination, and a positive photoresist. Even in low-k applications, printing contact holes at different dot pitches results in extremely high image quality. The inventors simulated the 125 nm point-to-point contact hole using 6% attenuation PSM and diagonal quadrupole (0.9 / 0.1) illumination, and when using radio-polarized light, the image was boosted. The results of this simulation are shown in Figures 14A-14C. The results shown in Figure 14 are also summarized in the following table: Polarization state minimum contrast minimum NILS* Non-polarization 0.64 1.85 Tangential polarization 0.58 1.77 Radio polarization 0.69 1.94 * NILS is normalized image registration slope -20- 1247339 ( 17) The invention is not limited to quadrupole illumination. Further examples include, but are not limited to, quasar illumination, four-fold symmetrical illumination, or any other illumination that approximates four-pole illumination. D. Polarization of Chromium-Free Alternating PSM Further improvement can be made by changing the attenuated phase shift mask to an alternating phase shift mask and maintaining the use of polarized light in the solvable point spacing of the joint. . D1·Chromium-free alternating PSM combined with radiated polarized light, with a 100-nm pitch nest contact as an example of a chrome-free alternating PSM layout checkerboard type selected, where the phase is at, for example, 〇° and 1 80 ° Alternate. The chrome-free alternating phase shift mask 1 500 graphic is shown in Figure 15. Emphasize the central position of the P S Μ 1 5 0 0 0 to show the different parts and phases. Parts 1 5 02 and 1 5 04 are areas that allow 1 〇 〇 % of light to pass through, with a phase of, for example, 0 °. The sections 1 5 0 6 and 1 5 0 8 are regions that allow 100% of the light to pass through, the phase of which is different from the phases of the portions 1502 and 1504. For example, portions 1506 and 1508 can have a phase of, for example, 180 degrees. Blackened area 1 5 1 〇 does not allow any light to pass through. Therefore, its transfer rate is 0%. As shown in Fig. 16, a repeating pattern of 10 〇 11111 dots from the contact holes is formed by transparent squares having alternating phases of 1 〇 〇 nm. For the layout of the mask, please refer to SPIE 4 8 89 (2 002), Levenson, MD, et al. "Vortex Mask: Forming 8 Onm Contact by Twisting", and International Patent-21 - (18) 1247339 WO 01/22164 A1 (2001), Grassman, Α, et al. "Form a contact hole by crossing a fast phase-shifting edge of a single phase mask." The resulting diffraction pattern of the contact array with illumination on the optical axis of the chrome-free mask is shown in Figure 17. For illumination on the optical axis, the lens does not capture the diffraction point because the (0,0), (1,〇) and (1,1) points are extinguished. For off-axis illumination, as depicted in Figure 17. In accordance with an embodiment of the invention, the (1,1) family of diffractive dots can be moved into the pupil. This will give you an image. For a pole, the image is equivalent to a one-dimensional grid. A two-dimensional image can be produced by synthesizing the X pole and the y pole. Figures 18A and 18B depict this two-dimensional image. The image can be enhanced by performing an optimum polarization of the two interfering diffraction points from each pole (in the example shown in Fig. 17B, the X-polarized light is the best). This is similar to the polar polarization pole with the Cartesian quadrupole. The simulation in air and resist (Fig. 18A-B) is at 0.93NA and 157.6nm wavelengths, and the illumination is Cartesian quadrupole (the diagonal quadrupole has no advantages, but can also be used). The quadrupole is radiopolarized. As long as the contact holes are printed in the negative photoresist, the simulations in both the air and the resist show nearly perfect contrast. NILS (calculated only in air) is extremely high (greater than 3, as shown in Figure 18 A). D2. Pitch-free effect of chrome-free contacts with radiated-polarized light The "forbidden" dot pitch in lithography has been explained. See SPIE 4000_ • 1 1 40 (2000), Socha, R. et al., “1 30 nm lithography and the following prohibited dot pitches”, and SPIE 46 8 9-.9 S 5 (2002), Shi, X · Etc. -22- 1247339 (19) People "understand the prohibition of the dot pitch phenomenon and assist in the configuration of special parts." For a particular illumination angle, the position of the dot pitch is prohibited from the field created by the destructive interference of the field between the special component and the main component. Difficulties will arise when attempting to print contact holes of a particular size at different dot pitches. See the work of Graevipner et al. The inventors used a common lighting condition and a common threshold to present synchronized exposures and to evaluate the extent of the repetitive processing window. For this set of simulations, the size of the transparent phase block forming a chrome-free mask (see Figure 16) is gradually increased from 100 nm to 100 nm, and the pitch is 25 nm. Figure 19 shows 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, and 100 nm. The various images produced by the best focus simulation of the dot pitch 〇 / As a result of the present invention, the image of the contact is generally sharp, but not very conspicuous in terms of the dot size. This is because the contacts are formed at the corners of the phase block. The threshold required to print a 50 nm contact at a distance of 10 nm is calculated as 〇 · 28 . At this threshold, look at the side lobes to develop a dot pitch between 400 nm and 500 nm (see Figure 19), and thus need to assist the special part to avoid printing the side lobes at a specific point. If the side lobes do not cause problems at other points, there is no need to assist the special parts. The NIL S and the contact width for all the pitches have been calculated at 〇 · 28 槛 (see Figures 20A and 20B, respectively). The contact width is the image width of the target threshold (〇 · 2 8 in this example), and NIL S is the registration slope of the image width when the same threshold is used. As shown in Fig. 20B, for a small dot pitch (about 20 〇 nm), the contact width changes almost linearly with the dot pitch; this is the system in which the image is exactly -23 - 1247339 (20) is a rectangle The sum of the dimension rasters. Outside this range, more diffraction points are accommodated in the pupil. Although not stated in the text, the depth of focus (DOF) shows that when more diffraction points contribute to the image, the change is from infinity (perfect mask, point source and wavefront) to finite. As shown in Figure 20A., the NILS for this pitch is considered to be above 2.5 for all dot pitches. This shows a good exposure space for all dot pitches. On the other hand, the contact width is varied from 50 nm to 105 nm (worst dot pitch) and is stably maintained at about 65 nm. This is extremely noteworthy, and has the advantages of simple mask layout, no dot-dependent pattern and illumination optimization. Please compare Graeupner et al., Socha, R. et al. with Shi, X. et al. D3. Custom Polarization In one embodiment, custom polarized light is used to replace simple radiated or tangentially polarized light. Figure 2 1 A shows a custom polarization pattern in which each arrow indicates the direction of the field vector for a particular portion of the beam. Fig. 21B shows another custom polarization pattern. Unlike radiation or tangential polarization, custom polarization patterns have inconsistent polarization vector designs. The polarization vector such as the channel shows the direction of the arrow in Figs. 21A and 21B. In one embodiment, the custom polarized light and the radiant and tangential polarization can be fabricated by a pattern polarizing device such as pattern polarizing device 104 or 202. The pattern in the pattern polarization device is preset, and the pattern polarization device can be changed as needed to produce the desired polarization. The shape of the illumination light for the lighting configuration or illumination source can also be customized. Provides custom lighting and the ability to customize polarization and intensity to optimize printing. -24 - (21) 1247339 E. Soaking lithography Other lithography techniques, immersion lithography can also be used for the printing of the contacts in the present invention. In the immersion lithography, at least the optical instrument and the wafer, such as the projection optical instrument 1 与 8 and the wafer 1 1 投影, are projected, and the space between them is filled with liquid. Using immersion lithography increases the dot pitch resolution from 125 nm to 100 nm. To simulate immersion lithography, the wavelength depends on the refractive index of the soaking solution (for example, 1.5). The liquid NA that can be achieved by a suitable lens design is 1.395. Figure 22 is an image of a 5 〇 nm contact hole simulating a 100 nm dot pitch in accordance with the immersion lithography of the present invention. The NILS exceeds 1.74, indicating that this is an optical lithography technique that can implement a 50 nm contact hole with a lOOnm pitch. F. Far Ultraviolet Radiation (EUV) Far Ultraviolet Radiation (EUV) is also viewed because it provides a very short wavelength and therefore has a high k factor at 100 nm. In-air image simulation using images of typical EUV conditions (0.6 PC, 0.25 NA, and binary contact hole masks with unpolarized light), confirming that EUV can print extremely high quality 5 Onm at 100 nm pitch Point image. The results of the simulation using the EUV according to the present invention are shown in Fig. 23. At DOP over 0.4 microns, the NILS and contrast are 〇·7 and 2.5 respectively; this shows that EUV provides good imagery under the right conditions. The inventors considered a number of methods for printing nest contact holes of I 〇〇 nm pitches, and found that 157 nm and high NA allow printing of 134 nm dot pitch contacts with good image quality. In addition, the radio-polarization combined with the most advanced method of 157 nm (slowing -25-1247339 (22) PSM, quadrupole, etc.) produces a more significant improvement over the use of unpolarized light. . The minimum point distance solved by this technique is 125 nm. Through radio-polarization, Cartesian quadrupole, chrome-free alternating PSM and negative photoresist, we can obtain contrast images of nearly 157 nm contact holes with a nearly perfect 10 () nm pitch. The inventors have found that this method is optimally up to 157 nm. The image quality was almost constant via the dot pitch, and the inventors did not observe the prohibited dot pitch. The inventors found that a hypothetical soaking solution of 1.5 refractive index at 157 nm produced a high quality image with a dot pitch of 100 nm, while the EUV condition produced a very high quality image with a 100 nm point contact. The simulation results are summarized in the table below. Method Wavelength (nm) ΝΑ Point Distance (nm) Contrast NILS Attenuation P s Μ and Unpolarized Light 157.6 0,93 134 0.5 1.55 Attenuated PSM and Radio Polarization 157.6 0.93 125 0.5 1 1.47 Chromium Free PSM and Radio Polarization 157.6 0.93 100 0.99 3.08 Soaking 157.6 1.395 100 0.62 1.74 EU V 13.4 0.25 100 0,99 5.27 While various embodiments of the invention have been described above, it is to be understood that It will be apparent to those skilled in the art that various changes in form and content may be made without departing from the spirit and scope of the invention. Therefore, the scope and scope of the invention should not be limited to the above-described embodiments, but only by the scope of the following patent application -26- 1247339 (23). BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in FIG. 1 is a lithography system in accordance with an embodiment of the present invention. 2 is a lithography system in accordance with an embodiment of the present invention. Figure 3 A is an enlarged image of the contact holes in the resist on the wafer. Figure 3B is a top view image of the contact hole in the resist on the wafer. 4A and 4B depict a mask spectrum of a two-dimensional attenuated illuminating phase shift mask (PSM) where px = Py = p and having off-axis off-axis illumination on an optical axis, respectively, in accordance with an embodiment of the present invention. Figure 5 shows an image with a finite pitch of unpolarized light, where c〇 and C45 are each rectangular and diagonally contrasted. Figure 6 depicts an example of a simulation experiment (showing radioactive polarization for the sake of illustration). Figures 7A and 7B show image quality effects of radiation and tangential polarization. Figures 8A-8C show a comparison of three polarization modes in an example of a 125-nm pitch (45 degree rotation mask). Figures 9A-9C depict the image quality effects of polarization. Figure 9A depicts a poor contrast image of a group of contact holes obtained using unpolarized light. Figure 9B depicts a poor contrast image of a group of contact holes obtained using tangentially polarized light. Figure 9C depicts a high contrast image of a group of contact holes obtained using radiantly polarized light, -27-(24) 1247339, in accordance with an embodiment of the present invention. Figure 1 〇 A depicts the effect of a tangent polarizer for the electric field vector in the light. Figure 10B depicts the effect of a radionilator for the electric field vector in the light. Figures 1 1 A and 1 1 B show the effect of the dot pitch of the radioactively polarized light with a chrome-free alternating PSM in accordance with an embodiment of the present invention. Figure 12 depicts the attenuation P S Μ. Figure 13 depicts a binary PSM. The images of Figures 14A - 14C show the polarization effect of image quality with a 125 nm pitch attenuation PSM in accordance with an embodiment of the present invention. Figure 15 depicts an alternate PSM. Figure 16 shows a chrome-free alternating PS Μ mask layout. Figures 17A and 17B show the optical axis and optical off-axis illumination of the diffraction pattern of the two-dimensional chrome-free alternating PSM, respectively. Figures 18A and 18B show images of chrome-free alternating PSM in air (a) and resist (b). Figure 19 shows the best focus relative to images in six airs using chrome-free alternating PSM and radio-polarized light with Cartesian quadrupole (C-quad). Figures 20A and 20B show image characteristics in air versus The pattern of the dot pitch. Figure 2 1 A and 2 ] B is an example diagram of custom polarization. Figure 22 is a immersion image of unpolarized light having a diagonal quadrupole and a 6% attenuation PSM of n = 1.5. Figure 23 shows the airborne image of the best 1247339 (25) in the extreme ultraviolet radiation (EUV) condition. Main component comparison table 100' 200 lithography system 102 illumination source 104, 202 pattern polarization device 106 mask 108, 204A, 204B projection optical instrument 110 wafer 302 resist layer 304 wafer surface 306 contact hole 10 0 2 Unpolarized light 1004 Tangential polarizer 1008 Radiated polarizer 10 10 Radiated polarized light 1200 Attenuated phase shift mask 1202, 1302 grid 1204 ^ 1304 Central portion 1206, 1306 Peripheral portion 1300 Binary phase shift mask 1500 No Chromium alternating phase shift mask 1502,] 504, 1506, 1508 part 15 10 blackened area

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Claims (1)

i iini··纠“"n—. It is annoyed that the members have clearly indicated whether the original case has been changed after the amendment of the case. The number of patents is 2247339. The scope of application for patents is attached. Attachment 2A: Patent No. 93 1 043 1 5 Patent Application for Chinese Patent Application: The amendment of the Republic of China on March 23, 1994 A method of printing on a wafer, comprising: (a) polarizing light according to a predetermined polarization pattern to produce a polarized exposure beam; (b) toward a mask and along an optical path Outputting the polarized exposure beam; (c) illuminating the mask with the polarized exposure beam in the optical path to produce an image in the exposure beam; and (d) exposing the exposure in the optical path The light of the beam exposes the photoresist layer on the wafer. 2. The method of claim 1, wherein the step (a) further comprises generating the polarized exposure beam in accordance with a radiation polarization pattern. 3. The method of claim 1, wherein the step (a) further comprises generating the polarized exposure beam in accordance with a linear polarization pattern. 4. The method of claim 1, wherein the step (a) further comprises generating the polarized exposure beam in accordance with a custom polarization pattern. 5. The method of claim 1, wherein the step (a) further comprises generating a polarized quadrupole illumination. 6. The method of claim 1, further comprising: · performing at step (a) Before 'pre-polarized light on the ~ illumination source 0 7. The method of claim 1, wherein the step (c) comprises illuminating a mask to produce an image comprising the contact holes. 8. The method of claim 1, wherein the step (d) occurs in a liquid. 9. The method of claim 1, wherein the mask is at least one of the group consisting of: a chromium-free phase shift mask, an attenuated phase shift mask, and an alternating phase shift mask. 10. The method of claim 1, wherein the mask is a binary mask. 1 1 · A method of printing on a wafer, comprising: (a) polarizing light according to a predetermined polarization pattern to produce a polarized exposure beam; (b) outputting the polarization along an optical path Exposing a beam of light; (c) illuminating a chrome-free phase shift mask with the polarized exposure beam in the optical path to produce an image in the exposure beam; (d) exposing the negative photoresist layer on the wafer with the light of the exposure beam in the optical path. 1 2 . A method of printing on a wafer, comprising: (a) polarizing light according to a predetermined polarization pattern to generate a polarized exposure beam; (b) outputting the pole along an optical path Exposing the beam of light; (c) illuminating an attenuated phase shift mask with the polarized exposure beam in the optical path to produce an image in the exposure beam; and (d) exposing the beam in the optical path Light on the wafer -2- 2 The positive photoresist layer is exposed. 1 3 . A method of printing on a wafer, comprising: (a) polarizing light according to a predetermined polarization pattern to generate a polarized exposure beam; (b) outputting the pole along an optical path Exposing the beam of light; (c) illuminating a binary mask with the polarized exposure beam in the optical path to produce an image in the exposure beam; (d) exposing the positive photoresist layer on the wafer with the light of the exposure beam in the optical path. 1 4. A method of printing on a wafer, comprising: (a) illuminating a phase shift mask with pre-polarized light to produce an image in the pre-polarized light; (b) obscuring the phase shift Covering and outputting the pre-polarized light along an optical path; (c) in a projection optical instrument of the optical path, the pre-polarized light is shaped by the polarized exposure beam to generate an exposure beam, wherein the pre-polarized light is based on a predetermined polarization pattern and And shaping the intensity pattern; and (d) exposing the photoresist layer on the wafer with the light of the exposure beam in the optical path. A lithography system comprising: (a) an illumination source that emits illumination light along an optical path; (b) a pattern polarization device that converts illumination light from the illumination source to a predetermined one Polarizing the exposure beam of the pattern and outputting the exposure beam to -3- 12473⁄4 The optical path; (C) a mask that produces an image in the exposure beam, wherein the mask includes a contact hole pattern having a little distance; and (d) a projection optical instrument that relays the exposure beam so that Print on a wafer. 16. The lithography system of claim 15, wherein the illumination light is pre-polarized illumination light, and wherein the pattern polarization device is a wave plate The lithography system of claim 15 wherein the illumination light is pre-polarized illumination light, and wherein the pattern polarization device is polarized by 18. 8 as claimed in claim 15 a lithography system, wherein the illumination light is non-polarized illumination light, and wherein the pattern polarization device is a polarizer 1 9. The lithography system according to claim 15 of the patent scope further includes ··(e) a wafer mounted to be exposed by the exposure beam. The lithography system of claim 19, further comprising a liquid that fills the space between the projection optical instrument and the wafer. 2 1. The lithography system of claim 15, wherein the pattern polarization device is included in the projection optical instrument. 22. The lithography system of claim 15, wherein the predetermined polarization pattern is a radio polarization pattern. 2 3. A lithography system as claimed in claim 15 wherein the predetermined polarization pattern is a linear polarization pattern. -4- 1247339 _ i丨年月日佐:More] is replacing the page Λ«»»«Μ6η*< rwsr«λ.·λ%wjwt*»*ajv --fnrn ι ιγ· ιιιίιγίιιί nryn ir ιιτιπητιιττι 24. For example, the lithography system of claim 15 wherein the predetermined polarization pattern is a custom polarization pattern. 2 5. The lithography system of claim 15 wherein the mask is one of the following groups, including: a chromium-free phase shift mask, an attenuated phase shift mask, a binary mask, and An alternating phase shifting mask. 26. A method of producing a contact hole on a wafer, comprising: (a) generating a polarized illumination beam; (b) illuminating a mask with the polarized illumination beam to produce an exposure beam The mask creates a contact hole pattern having a slight distance in the exposure beam; and (c) exposing a wafer to the light of the exposure beam. 27. The method of claim 26, wherein the step (b) further comprises illuminating a phase shift mask. 28. The method of claim 26, wherein the step (a) further comprises generating a radiation-polarized illumination beam. 2 9. The method of claim 26, wherein the step (a) further comprises generating all linearly polarized illumination beams. The method of claim 26, wherein the step (a) further comprises generating a customized polarized illumination beam.